Square-holed old Japanese coins

Many of the old Japanese coins were minted in a circular or oval shape, having a square hole in the middle. Similar coins are to be found throughout the entire Asia, all of them derived from a type of coins minted in China more than two thousand years ago.

An interesting fact is that the square hole had a practical purpose, because this way the coins were easily carried (and counted) strung together on a string. At the same time, the square hole was considered bringing good luck, because it was combining the round shape of the coin, symbolizing the sky, with a square shape symbolizing the earth.